During the drilling, completion, and production phases of wells for petroleum, the downhole use of compositions having higher viscosities is important for a wide variety of purposes. Such fluids can more effectively carry materials (e.g., proppants, gravel, and the like) to a desired location downhole. Similarly, such fluids can more effectively carry materials away from a drilling location downhole. Further, the use of such fluids during hydraulic fracturing generally results in larger, more dominant fractures. However, during pumping downhole, high viscosity liquids can generate high friction pressure, which can make pumping less efficient.